KELLICOTTIA BOSTONIENSIS (ROUSSELET, 1908) AND K. LONGISPINA (KELLICOTT, 1879) (ROTIFERA: BRACHIONIDAE): THE PATTERN OF THE OCCURRENCE AND SPREAD IN THE LAKES IN THE UPPER AND MIDDLE VOLGA

Abstract

In lakes of the Upper Volga (Yaroslavl district) and in the lower course of the Sura River (Middle Volga), closely related rotifers - common for both studied regions native K. longispina and alien K. bostoniensis - were found. Both species occur all year round and more frequently in spring or autumn, when they are the most abundant. Alien rotifer K. bostoniensis occurred not only simultaneously with indigenous species, but also separately, in more shallow waterbodies. Alien species is more tolerate to bathymetry, basin form, transparency and the trophy state of the waterbody. This likely facilitates wider distribution of the K. bostoniensis in the Sura basin waterbodies compared to indigenous species. Alien species K. bostoniensis spread relatively quickly in the Sura basin without any harm to closely related indigenous species, to which it is not a competitor.